DragGestureRecognizer
Class DragGestureRecognizer
- java.lang.Object
-
- java.awt.dnd.DragGestureRecognizer
- All Implemented Interfaces:
- Serializable
- Direct Known Subclasses:
- MouseDragGestureRecognizer
public abstract class DragGestureRecognizer extends Object implements Serializable
The DragGestureRecognizer
is an abstract base class for the specification of a platform-dependent listener that can be associated with a particular Component
in order to identify platform-dependent drag initiating gestures.
The appropriate DragGestureRecognizer
subclass instance is obtained from the DragSource
associated with a particular Component
, or from the Toolkit
object via its createDragGestureRecognizer()
method.
Once the DragGestureRecognizer
is associated with a particular Component
it will register the appropriate listener interfaces on that Component
in order to track the input events delivered to the Component
.
Once the DragGestureRecognizer
identifies a sequence of events on the Component
as a drag initiating gesture, it will notify its unicast DragGestureListener
by invoking its gestureRecognized()
method.
When a concrete DragGestureRecognizer
instance detects a drag initiating gesture on the Component
it is associated with, it fires a DragGestureEvent
to the DragGestureListener
registered on its unicast event source for DragGestureListener
events. This DragGestureListener
is responsible for causing the associated DragSource
to start the Drag and Drop operation (if appropriate).
- See Also:
-
DragGestureListener
,DragGestureEvent
,DragSource
, Serialized Form
Fields
dragSource
protected DragSource dragSource
The DragSource
associated with this DragGestureRecognizer
.
component
protected Component component
The Component
associated with this DragGestureRecognizer
.
dragGestureListener
protected transient DragGestureListener dragGestureListener
The DragGestureListener
associated with this DragGestureRecognizer
.
sourceActions
protected int sourceActions
An int
representing the type(s) of action(s) used in this Drag and Drop operation.
events
protected ArrayList<InputEvent> events
The list of events (in order) that the DragGestureRecognizer
"recognized" as a "gesture" that triggers a drag.
Constructors
DragGestureRecognizer
protected DragGestureRecognizer(DragSource ds, Component c, int sa, DragGestureListener dgl)
Construct a new DragGestureRecognizer
given the DragSource
to be used in this Drag and Drop operation, the Component
this DragGestureRecognizer
should "observe" for drag initiating gestures, the action(s) supported for this Drag and Drop operation, and the DragGestureListener
to notify once a drag initiating gesture has been detected.
- Parameters:
-
ds
- theDragSource
thisDragGestureRecognizer
will use to process the Drag and Drop operation -
c
- theComponent
thisDragGestureRecognizer
should "observe" the event stream to, in order to detect a drag initiating gesture. If this value isnull
, theDragGestureRecognizer
is not associated with anyComponent
. -
sa
- the set (logical OR) of theDnDConstants
that this Drag and Drop operation will support -
dgl
- theDragGestureRecognizer
to notify when a drag gesture is detected - Throws:
-
IllegalArgumentException
- if ds isnull
.
DragGestureRecognizer
protected DragGestureRecognizer(DragSource ds, Component c, int sa)
Construct a new DragGestureRecognizer
given the DragSource
to be used in this Drag and Drop operation, the Component
this DragGestureRecognizer
should "observe" for drag initiating gestures, and the action(s) supported for this Drag and Drop operation.
- Parameters:
-
ds
- theDragSource
thisDragGestureRecognizer
will use to process the Drag and Drop operation -
c
- theComponent
thisDragGestureRecognizer
should "observe" the event stream to, in order to detect a drag initiating gesture. If this value isnull
, theDragGestureRecognizer
is not associated with anyComponent
. -
sa
- the set (logical OR) of theDnDConstants
that this Drag and Drop operation will support - Throws:
-
IllegalArgumentException
- if ds isnull
.
DragGestureRecognizer
protected DragGestureRecognizer(DragSource ds, Component c)
Construct a new DragGestureRecognizer
given the DragSource
to be used in this Drag and Drop operation, and the Component
this DragGestureRecognizer
should "observe" for drag initiating gestures.
- Parameters:
-
ds
- theDragSource
thisDragGestureRecognizer
will use to process the Drag and Drop operation -
c
- theComponent
thisDragGestureRecognizer
should "observe" the event stream to, in order to detect a drag initiating gesture. If this value isnull
, theDragGestureRecognizer
is not associated with anyComponent
. - Throws:
-
IllegalArgumentException
- if ds isnull
.
DragGestureRecognizer
protected DragGestureRecognizer(DragSource ds)
Construct a new DragGestureRecognizer
given the DragSource
to be used in this Drag and Drop operation.
- Parameters:
-
ds
- theDragSource
thisDragGestureRecognizer
will use to process the Drag and Drop operation - Throws:
-
IllegalArgumentException
- if ds isnull
.
Methods
registerListeners
protected abstract void registerListeners()
register this DragGestureRecognizer's Listeners with the Component subclasses must override this method
unregisterListeners
protected abstract void unregisterListeners()
unregister this DragGestureRecognizer's Listeners with the Component subclasses must override this method
getDragSource
public DragSource getDragSource()
This method returns the DragSource
this DragGestureRecognizer
will use in order to process the Drag and Drop operation.
- Returns:
- the DragSource
getComponent
public Component getComponent()
This method returns the Component
that is to be "observed" by the DragGestureRecognizer
for drag initiating gestures.
- Returns:
- The Component this DragGestureRecognizer is associated with
setComponent
public void setComponent(Component c)
set the Component that the DragGestureRecognizer is associated with registerListeners() and unregisterListeners() are called as a side effect as appropriate.
- Parameters:
-
c
- TheComponent
ornull
getSourceActions
public int getSourceActions()
This method returns an int representing the type of action(s) this Drag and Drop operation will support.
- Returns:
- the currently permitted source action(s)
setSourceActions
public void setSourceActions(int actions)
This method sets the permitted source drag action(s) for this Drag and Drop operation.
- Parameters:
-
actions
- the permitted source drag action(s)
getTriggerEvent
public InputEvent getTriggerEvent()
This method returns the first event in the series of events that initiated the Drag and Drop operation.
- Returns:
- the initial event that triggered the drag gesture
resetRecognizer
public void resetRecognizer()
Reset the Recognizer, if its currently recognizing a gesture, ignore it.
addDragGestureListener
public void addDragGestureListener(DragGestureListener dgl) throws TooManyListenersException
Register a new DragGestureListener
.
- Parameters:
-
dgl
- theDragGestureListener
to register with thisDragGestureRecognizer
. - Throws:
-
TooManyListenersException
- if aDragGestureListener
has already been added.
removeDragGestureListener
public void removeDragGestureListener(DragGestureListener dgl)
unregister the current DragGestureListener
- Parameters:
-
dgl
- theDragGestureListener
to unregister from thisDragGestureRecognizer
- Throws:
-
IllegalArgumentException
- if dgl is not (equal to) the currently registeredDragGestureListener
.
fireDragGestureRecognized
protected void fireDragGestureRecognized(int dragAction, Point p)
Notify the DragGestureListener that a Drag and Drop initiating gesture has occurred. Then reset the state of the Recognizer.
- Parameters:
-
dragAction
- The action initially selected by the users gesture -
p
- The point (in Component coords) where the gesture originated
appendEvent
protected void appendEvent(InputEvent awtie)
Listeners registered on the Component by this Recognizer shall record all Events that are recognized as part of the series of Events that go to comprise a Drag and Drop initiating gesture via this API.
This method is used by a DragGestureRecognizer
implementation to add an InputEvent
subclass (that it believes is one in a series of events that comprise a Drag and Drop operation) to the array of events that this DragGestureRecognizer
maintains internally.
- Parameters:
-
awtie
- theInputEvent
to add to thisDragGestureRecognizer
's internal array of events. Note thatnull
is not a valid value, and will be ignored.
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